Brushless motor and its assembly method

ABSTRACT

Brushless motors for portable information equipment that can be simultaneously reflow-soldered to a substrate and efficiently and densely mounted thereon in such a way that the coupled portion between the motor and the substrate has a high impact resistance, thereby providing small and reliable portable information equipment having a high productivity. The brushless motor including a housing having a bottom surface, a side surface, and a top surface, the bottom surface being located adjacent and opposite to a substrate of equipment; a plurality of lands ( 2   a,    2   e ) on the bottom surface that can be mechanically or electrically joined with the substrate of the equipment; a stator ( 1 ), a bearing device ( 3 ), and a rotor ( 4 ) inside said housing, the stator ( 1 ) having a stator core ( 6 ) and a coil ( 7 ) wound around the stator core ( 6 ), the rotor ( 4 ) having a magnet ( 13 ) and being supported by the bearing device ( 3 ) so as to rotatably surround the periphery of the stator ( 1 ), the rotor ( 4 ) further including a circular weight ( 14 ).

This is a Division of application Ser. No. 09/499,617, filed Feb. 7,2000, which in turn is a continuation-in-part of application Ser. No.09/401,987, filed Sep. 23, 1999 now abandoned.

FIELD OF THE INVENTION

The present invention relates to the structure of a small flat brushlessmotor and its assembly method,

BACKGROUND OF THE INVENTION

Portable information equipment (hereafter referred to as “equipment”)including, for example, cellular telephones are desired to be smaller,lighter, and thinner, to give a sophisticated impression, and to endurelongtime use. Equipment manufacturers are making various efforts to meetthese demands. They are attempting to reduce the size and powerconsumption of electronic parts integrated into the equipment, to usemultilayer wiring substrates to allow electronic parts to be denselyintegrated while increasing productivity, and to configure enclosuresusing light metal such as magnesium to reduce the thickness of theequipment and give it a sophisticated impression. There are similardemands on flat brushless motors used as a drive source for theequipment.

A vibration generating function for silent calls is now essential forcellular telephones. The vibration generating function is generallyimplemented by a vibrating motor with an eccentric weight. This isbecause such a motor has excellent characteristics such as a small size,a low power consumption, and a low price and is thus advantageous inreducing the weight of the equipment. The vibrating motor must alsoserve to improve the value of the equipment.

Requirements on vibrating motors and flat brushless motors used asequipment drive sources (hereafter, these motors may be collectively andsimply referred to as “brushless motor” or “motors”) that should to bemet to improve the value of the equipment will be considered. First,brushless motors must be adapted for the improved degree of integrationof the equipment. Thus, as in other solid electronic parts, thebrushless motor can desirably be mounted on a substrate of the equipmentusing “surface mount technology.” This is because in case of amultilayer substrate, the degree of integration may decrease ifterminals are passed through holes formed in the substrate. In order toimprove the degree of integration, the brushless motor is desirablyconfigured by being mounted close to adjacent electronic parts so as toachieve a high density.

Second, the brushless motor must be adapted for the same mountingprocess as other solid electronic parts in order to increase theproductivity of the equipment. Thus, the brushless motor desirably has aconfiguration and a heat resistance compatible with a reflow solderingmethod. It is also desirably configured by being efficiently mountedusing the same assembly machine as other solid electronic parts.

Third, the brushless motor must be adapted for the reduced size andweight of the enclosure of the equipment. Thus, it desirably has a highimpact resistance.

The reasons for the demand for the high impact resistance will bedescribed. Of course, the high impact resistance is required to ensurethat the equipment will not be destroyed even if it is inadvertentlydropped. Conventional common methods provide a certain amount of spaceinside the equipment and integrate the motor into the equipment via anelastic body. In recent years, however, the demand for reduced size andthickness prevents a space for the elastic body from being provided. Ifan attempt is made to surface-mount the motor on the same substrate asother electronic parts in order to meet the demand, the brushless motoris directly fixed to the substrate, thereby preventing impacts to beabsorbed as in elastic support structures.

Furthermore, attempts are being made to form the enclosure of theequipment of light metal such as magnesium or aluminum, as describedabove. Despite its small weight, such metal has a much higher rigiditythan resin so its buffering capability is insufficient. Consequently, anunprecedentedly large impact is effected on the substrate fixed to theenclosure and is directly transmitted to the motor fixed to thesubstrate. As a result, a very high impact resistance is required of themotor and its coupling. Therefore, the desired value of motor impactresistance is conventionally between 3,000 and 5,000 G but now between10,000 and 20,000 G.

Besides, this impact resistance is desirably met by simply heating andmelting a solder on the substrate to solder-connect the motor to thesubstrate (reflow) without passing terminals through holes formed in thesubstrate (surface mount). Even enduring a reflow heating temperature(about 250° C.) is difficult. The inventor attempted to find aconventional technique that meets these requirements, but in vain. Thus,through many examinations, the inventor has completed the presentinvention. A motor according to the present invention is of a flat typehaving a height smaller than the breadth, so it is sometimes referred toas a “flat vibrating motor” or a “flat brushless motor.”

Next, brushless motors will be described by focusing on conventionalassembly methods.

A small flat brushless motor generally comprises a metal base on whichvarious parts are assembled. Since the motor is a rotational powersource for the equipment, it must be mounted in the equipment so as tomaintain a sufficient rigidity and the metal base must be formedaccurately so as to be suitable as a criterion for motor assembly. Toassemble the motor, the base is placed on a palette (a positioningworking table) and the parts are then mounted on the base.

According to this assembly method, before placing the base on thepalette, whether or not the base is located upside down is checked andits direction and position are adjusted. The time required for thisoperation, however, tends to increase with decreasing size of the motor.This is because it is more difficult to handle smaller parts. Thistendency is found not only in the positioning of the motor base but alsoin the assembly of electronic parts on a printed circuit board. Theelectronic parts are difficult to efficiently mount on a small printedcircuit board.

In addition to the reduced size, there is a strong demand for thereduced weight of the motor for portable equipment. However, inattempting to reduce the size and weight of the motor, thecharacteristics of the motor must not be sacrificed. Thus, a rotor and astator must naturally have a specified size and weight. Accordingly, itis now necessary to reduce the volume and weight of peripheral membersincluding structures other than the rotor and stator, that is, astructure for holding the rotor and stator and a structure forelectrically connecting the stator and external device together.

The printed circuit board assembly method called the “connectedsubstrate” is conventionally commonly used to produce built-in circuitsfor various equipment. When printed circuit boards have small ordifferent external shapes, this method arranges a large number of suchcircuit boards and connects them together using bridges or frames so asto form a shape that is easily handled by an electronic parts mountingmachine. After electronic parts have been mounted on these circuitboards, the bridges are cut and removed to obtain printed circuit boardassemblies in order to complete assembly.

This method, however, is still disadvantageous if further size reductionis required. In addition, as the size of the printed circuit boarddecreases, the area occupied by the bridges or frames relativelyincreases to reduce the usage of material resources. In addition,despite a demand for further reduction of the size of the printedcircuit board, when a shearing machine is used to cut the bridges,contacts with the cutting edge and stress caused by shearing must beavoided. As a result, no part can be placed near the sheared position.The bridges may be folded or ruptured, but the separated portion form arough rupture surface to degrade the appearance and dimensionalaccuracy. Due to these disadvantages, this method is unsuitable forsmall parts. Furthermore, since the separation is carried out after thecompletion of assembly, an impact associated with shearing may degradethe quality of finished products.

Thus, an assembly method is desired that solves these problems inconfiguring a compact motor by mounting parts on a printed circuit boarddensely.

In attempting to meet these demands, another object is to reduce thevolume and weight of the members such as the structure for holding therotor and stator and the structure for electrically connecting thestator and external device together.

OBJECTS OF THE INVENTION

A first object of the present invention is to meet the aboverequirements, that is, to contribute to improving the degree ofintegration of the equipment. Thus, the motor must be configured bybeing mounted on the substrate of the equipment using the SMT technologyand to be mounted close to adjacent electronic parts so as to achieve ahigh density.

A second object is to contribute to improving the productivity of theequipment. Thus, the motor must have a configuration and a beatresistance compatible to the reflow soldering method and must beconfigured by being efficiently mounted using the same assembly machine.

A third object is to contribute to reducing the size and weight of theequipment. Thus, the motor must have a sufficient impact resistance.

A fourth object is to improve the assembly productivity. Thus, thepresent invention must provide a structure that is easier to handle andassemble and an assembly method for such a structure.

A total object of the present invention is to attain the above objectsto provide portable information equipment having a reduced size andweight, an increased productivity, and high added values.

DISCLOSURE OF THE INVENTION

In order to attain these objects, a brushless motor according to thepresent invention comprises a housing comprising a bottom surface, aside surface, and a top surface, the bottom surface being locatedadjacent and opposite to a substrate of an equipment; pairs of terminalson the bottom surface that can be mechanically or electrically joinedwith the substrate of the equipment; a stator, a bearing device, and arotor inside the housing, the stator having a stator core and a coilwound around it, the rotor having a magnet and supported by the bearingdevice so as to rotatably surround the periphery of the stator, therotor further including unbalance means or housing drive means thatprotrudes from part of the housing and that rotates with the rotor.

In addition, in order to solve the problems with the assembly of thebrushless motor, a motor assembly method according to the presentinvention uses a motor base connector. The motor base connectorcomprises motor bases each using a plate-like material as a basematerial and comprises a plurality of motor bases and a skeleton thatremains after these motor bases have been punched out, the plurality ofmotor bases being pushed back and held in the skeleton. Each motor baseis completed by executing the steps of fixing the bearing device and thestator to a stator mounting surface, assembling the rotor on the bearingdevice, and removing the motor from the skeleton.

Next, the structure of the brushless motor and its assembly methodaccording to the present invention are described in detail.

First, a flat brushless motor according to a first aspect of the presentinvention is adapted to meet the following requirements:

(a) The motor has a housing comprising a bottom surface, a side surface,and a top surface.

(b) The bottom surface is located adjacent and opposite to a substrateof an equipment. The motor has on this bottom surface, pairs ofterminals that can be mechanically or electrically joined with thesubstrate of the equipment. The pairs of terminals are arranged on bothsides around a line passing through the centroid or center of gravity ofthe bottom surface.

(c) The motor comprises a stator, a bearing device, and a rotor, allinside the housing. The stator has a stator core and a coil wound aroundthe stator core. The rotor has a magnet and is supported by the bearingdevice so as to rotatably surround the periphery of the stator.

(d) The rotor further includes unbalance means.

With these terminals, the motor can be joined with the substrate of theequipment by reflow soldering method (solder joint) . The housingfacilitates handling of the motor. When prevented from protruding fromthe bottom surface area outward sideways, the terminals on the bottomsurface can be arranged close to adjacent electronic parts. In addition,through the terminals may further protrude perpendicularly from thebottom surface so as to engage with holes in the substrates of theequipment, such an embodiment that the terminals are surface-connectedto the substrate of the equipment is essentially desirable for theequipment.

In addition, since the terminals are arranged so as not to concentratein part of the bottom surface, they can cooperate in efficiently bearingan impact, thereby providing a large holding force. Desirably, theimpact can be more evenly shared by arranging the terminals point-,line-, or rotation-symmetrically around the centroid or center ofgravity of the bottom surface.

According to more detailed explanation, the expression “center ofgravity” may be paraphrased as a point where the center of gravity onthe whole is vertically projected on the bottom surface. Furthermore,the centroid means the center of gravity on a plane figure.

A flat brushless motor according to a second embodiment of the presentinvention is adapted to meet the following requirements:

(a) The motor has a housing comprising a bottom surface, a side surface,and a top surface.

(b) The bottom surface is located adjacent and opposite to a substrateof an equipment. The motor has on this bottom surface, pairs ofterminals that can be mechanically or electrically joined with thesubstrate of the equipment. The pairs of terminals are arranged on bothsides around a line passing through the centroid or the center ofgravity of the bottom surface.

(c) The motor comprises a stator, bearing device, and a rotor, allinside the housing. The stator has a stator core and a coil wound aroundthe stator core. The rotor has a magnet and is supported by the bearingdevice so as to rotatably surround the periphery of the stator.

(d) External drive means that rotate with the rotor protrudes from partof the housing.

Preferably, the external drive means protruding from the housing is, forexample, a shaft, a gear, a pulley, or part of the rotor. It reasonablyprotrudes from the top surface but may protrude from the bottom surfaceor part of the side surface depending on the requirements on theequipment.

A flat brushless motor according to a third embodiment of the presentinvention is adapted to meet the following requirements:

(a) The motor has a housing comprising a bottom surface, a side, and atop surface.

(b) The bottom surface is located adjacent and opposite to a substrateof equipment. The motor has on the side of the housing, pairs ofterminals that protrude from the side approximately at the same heightas the bottom surface and that can be mechanically or electricallyjoined with the substrate of the equipment. The pairs of terminals arearranged on both sides around a line passing through the centroid orcenter of gravity of the bottom surface.

(c) The motor comprises a stator, a bearing device, and a rotor, allinside the housing. The stator has a stator core and a coil wound aroundit. The rotor has a magnet and is supported by the bearing device so asto rotatably surround the periphery of the stator.

(d) The rotor further comprises unbalance means.

In this manner, the terminals protrude from the side of the housing, sothese terminals can be provided in addition to the terminals within thebottom surface area to further increase the number of terminals, therebyincreasing fixing strength. This configuration may also correspond tothe reflow method that locally heats the protruding terminals.

A flat brushless motor according to a fourth embodiment of the presentinvention is adapted to meet the following requirements:

(a) The motor has a housing comprising a bottom surface, a side, and atop surface.

(b) The bottom surface is located adjacent and opposite to a substrateof equipment. The motor has on the side of the housing, pairs ofterminals that protrude from the side approximately at the same heightas the bottom surface and that can be mechanically or electricallyjoined with the substrate of the equipment. The pairs of terminals arearranged on both sides around a line passing through the centroid orcenter of gravity of the bottom surface.

(c) The motor comprises a stator, a bearing device, and a rotor, allinside the housing. The stator has a stator core and a coil wound aroundthe stator core. The rotor has a magnet and is supported by the bearingdevice so as to rotatably surround the periphery of the stator.

(d) External drive means that rotate with the rotor further protrudesfrom part of the housing.

In this manner, the terminals protrude sideways of the housing, as inthe motor according to the third embodiment, so these terminals can beprovided in addition to the terminals within the bottom surface area tofurther increase the number of terminals, thereby increasing fixingstrength. This configuration may also correspond to the reflow methodthat locally heats the protruding terminals.

A flat brushless motor according to a fifth embodiment of the presentinvention is adapted to meet the following requirements:

(a) The motor has a housing comprising a bottom surface, a side surface,and a top surface and further comprising a chuck section.

(b) The bottom surface is located adjacent and opposite to a substrateof equipment. The motor has on the bottom surface or side of thehousing, pairs of terminals that can be mechanically or electricallyjoined with the substrate of the equipment. The pairs of terminals arearranged on both sides around a line passing through the centroid orcenter of gravity of the bottom surface.

(c) The motor comprises a stator, a bearing device, and a rotor, allinside the housing. The stator has a stator core and a coil wound aroundit. The rotor has a magnet and is supported by the bearing device so asto rotatably surround the periphery of the stator.

(d) The rotor further comprises unbalance means.

This housing enables the motor to be transferred by using a loadingchuck of an automatic electronic parts assembly machine and then to beautomatically loaded on and soldered to the substrate of the equipment.The chuck section desirably accommodates a suction chuck, a grip chuck,and a magnet chuck, as shown below.

A flat brushless motor according to a sixth embodiment of the presentinvention is adapted to meet the following requirements:

(a) The motor has a housing comprising a bottom surface, a side surface,and a top surface and further comprising a chuck section.

(b) The bottom surface is located adjacent and opposite to a substrateof equipment. The motor has on the bottom surface or side of thehousing, pairs of terminals that can be mechanically or electricallyjoined with the substrate of the equipment. The pairs of terminals arearranged on both sides around a line passing through the centroid orcenter of gravity of the bottom surface.

(c) The motor comprises a stator, a bearing device, and a rotor, allinside the housing. The stator has a stator core and a coil wound aroundthe stator core. The rotor has a magnet and is supported by the bearingdevice so as to rotatably surround the periphery of the stator.

(d) External drive means that rotate with the rotor further protrudesfrom part of the housing.

As in the motor according to the fifth embodiment, this housing enablesthe motor to be transferred by using a loading chuck of an automaticelectronic parts assembly machine and then to be automatically loaded onand soldered to the substrate of the equipment. The chuck sectiondesirably corresponds to a suction chuck, a grip chuck, and a magnetchuck, as shown below.

In addition, according to the flat brushless motor of the presentinvention, the chuck section comprises a sucked surface that is locatedon the top surface and to which a suction chuck can be opposed. Thissucked surface enables the motor to corresponds to suction chucks mostcommonly used in electronic parts assembly machines. The size of thesucked surface on the top surface conforms to many automatic assemblymachines if the surface is flat and has a diameter of at least 3 mm ormore and desirably 4 mm or more. The sucked surface may be shaped like aring. Both an inclined surface and a spherical surface can be chucked.

In addition, according to the brushless motor of the present invention,the chuck section comprises two parallel planes located on the side andextending approximately perpendicularly to the bottom surface or twoparallel ridges located on the side and extending parallel with thebottom surface. This configuration enables the electronic parts assemblymachine to easily grip, load, and align the motor and also enablesalignment to be checked easily. Alignment can also be carried out byusing a grip chuck to clamp the two parallel ridges extending parallelwith the bottom surface. If the motor appears like an n-gon as seen fromthe top surface ((n) is an even number larger than or equal to four),the shape of the motor is similar to a circle and thus serves to savespace, while it allows the motor to be gripped by the chuck. If themotor appears like an oval or a similar shape as seen from the topsurface, this shape contributes to further enlarging the internal spaceand is preferable in housing inside other electronic parts such as adrive circuit. If the motor appears like two parallel lines locatedadjacent to the outer circumference of a circle as seen from the topsurface, the shape of the motor is very similar to a circle and thusserves to save space, while it allows the motor to be gripped by thechuck. If the motor appears like a combination of a base having twoparallel planes and a cylinder, a cover shaped like a cylindrical cupcan be easily produced to reduce costs. If an arch-shaped cover ismounted on the base in such a way as to surround the outside of therotor, then despite the lack of protection for the inside of the motor,the arch-shaped cover contributes to saving resources to reduce costs.

In addition, the chuck section of the brushless motor of the presentinvention comprises a ferromagnetic member forming the top surface. Thisferromagnetic member on the top surface enables the motor to betransferred by an automatic assembly machine using a magnet chuck. Theferromagnetic member is preferably a plated copper plate or a magneticstainless steel plate.

In addition, the brushless motor of the present invention further has onthe top surface or side, a marking for enabling the mounting directionof the motor to be determined. With this marking for enabling themounting direction of the motor to be determined, the motor can beloaded in the correct direction by using an automatic assembly machine.The marking may exhibit a reflectance or magnetic reaction differentfrom that of the periphery or may protrude or be recessed relative tothe periphery. The method is selected depending on the structure andsize of the motor and the configuration of an equipment assemblyfacility.

In addition, according to the brushless motor of the present invention,the number of terminals on the bottom surface is larger than the numberof poles required for electric connections. Thus, the bottom surface hasthe large number of terminals including those required for electricconnections, thereby increasing the strength with which the motor ismounted on the substrate to improve the impact resistance. In any of themotors, the basic concept is that the terminal has a high mechanicaljunction function for supporting a required weight, but separate holdingmeans may be added that comprises an elastic body placed between the topsurface and the enclosure of the equipment. The terminal may be formedof a land, a plate, a wire, or a headed pin. The bottom surface need notbe the overall bottom surface but may be substantially formed of thebottom-side end surfaces of the side walls. In addition, although aconfiguration in which an output shaft for obtaining an output does notprotrude to the exterior is preferable in protecting the interior, therotor may partly protrude as required.

In addition, according to the flat brushless motor of the presentinvention, the top surface and side of the housing approximatelysurround the overall circumference of the rotor. In this manner, theouter rotor is further covered by the housing so as to be shielded, sothe inside can be protected from the entry of hot blasts or dusts. Thus,this motor is suitable for the reflow method.

In addition, a tape-like package according to the present invention hasa plurality of embosses arranged in series and in which the flatbrushless motor is accommodated. Thus, the motor is supplied from thetape-like package, it can be efficiently mounted on the substrate of theequipment like electronic parts, using an automatic assembly machine.

In addition, a portable information equipment according to the presentinvention comprises the flat brushless motor of the present invention.Accordingly, the motor having the above characteristics can be reliablymounted so as to provide a high productivity, thereby increasing thevalue of the equipment.

In addition, the flat brushless motor of the present invention has apositioning member protruding from the bottom surface. Since the bottomsurface has the positioning member for positioning relative to therelevant equipment, the external drive means can be accurately mounted.The positioning member is reasonably formed coaxially with the bearingdevice.

Next, a motor base connector according to the present invention isadapted to meet the following requirements:

(a) The motor base connector comprises motor bases each using aplate-like material as a base material.

(b) The motor base connector comprises a plurality of motor bases and askeleton that remains after these motor bases have been punched out.

(c) The plurality of motor bases are pushed back and held in theskeleton.

Pores for positioning the skeleton are preferably provided in theskeleton. These structures allow the motor bases to be held by theskeleton, so this motor base connector is suitable for automaticassembly. In addition, by providing slit near the motor base in theskeleton, stress in the skeleton caused by the push-back is reduced toalleviate warp and deformation.

The motor base is a plate having a bottom surface, a stator mountingsurface opposed to the bottom surface, and an outer circumferentialside, the stator mounting surface having the stator fixed thereto. Themotor base is desirably a printed circuit board, a ceramic substrate, ora metal substrate comprising a plate-like insulating material as a basematerial. In particular, double-side printed circuit boards are mostpreferable because they serve to reduce the size and weight of themotor.

In addition, a brushless motor assembly method according to the presentinvention is adapted to meet the following requirements:

(a) The motor base connector, the stator, the bearing device, and therotor are used.

(b) Each motor base has a stator mounting surface and a bottom surface.The method comprises the steps of fixing the bearing device and thestator to the stator mounting surface, assembling the rotor on thebearing device, and removing the motor from the skeleton.

In this manner, the motor base can be handled as a connector, so theposition and direction of the motor base can be regulated veryaccurately and a high-quality motor can be promptly assembled using aparts mounting machine. In addition, since no shearing operation is usedto remove the motor from the skeleton, there is no possibility ofquality degradation caused by an impact associated with shearing.

The method may include the steps of heating and hardening an adhesivefor all the motors, carrying out batch reflow soldering, installing acover, or conducting inspections, or as required. In addition, the motormay have either a cored outer rotor structure or a planar opposedcore-less structure, but in the planar opposed core-less type, the motorcan act as a magnetic path if the motor base comprises an ironsubstrate.

In addition, a brushless motor according to a seventh embodiment of thepresent invention is adapted to meet the following requirements:

(a) The motor comprises a stator, a base, a bearing device, and a rotor.

(b) The stator has a stator core and a coil wound around the statorcoil.

(c) The base is a plate-like substrate comprising an electric insulatingmaterial as a base material and having a bottom surface, a statormounting surface opposed to the bottom surface, and an outercircumferential side. At least part of the outer circumferential side ortwo or more portions thereof are exposed so as to be held by a skeleton.The bearing device and the stator are fixed coaxially to the statormounting surface. Pairs of terminals are arranged on the bottom surfaceor the stator mounting surface.

(d) The rotor has a rotor yoke and a magnet fixed to the rotor yoke. Therotor yoke surrounds the periphery of the stator and is rotatablysupported by the bearing device.

The base is desirably a resin substrate or a printed circuit board. Withthis base, the external size of the motor can be made as small as thediameter of the rotor by attaching the terminals to the bottom surfaceand the stator side and electrically connecting the terminals togetherthrough the plate material. The terminal may be formed of a land, aplate, a wire, or a headed pin. In addition, since at least part of theouter circumferential side or two or more portions thereof are exposedso as to be held by the skeleton, a reasonable assembly method can beprovided in which the motor base is transferred as a connector.

Furthermore, in the brushless motor according to the present invention,the base is a double-side printed circuit board, and a plurality oflands are provided on each of the bottom surface and the stator side.This base comprising a double-side printed circuit board provides a heatresistance for soldering in motor assembly, a mechanical strength forholding the motor, and a compatibility with a method for transferringthe motor by holding its outer circumferential side. By connecting themutually corresponding lands together via through-holes, electricconnections can be established while providing a light and compactmotor. In addition, by providing through-holes in an outer circumferencepunching section, the cover can be inserted into the through-holes andfixed at the outer circumferential end of the motor base. Thisconfiguration is preferable in providing a cover having approximatelythe same size as the motor base.

Moreover, the portable information equipment according to the inventioncomprises a brushless motor which is surface-mounted on the substrate ofthe equipment. Thus, without providing fixing holes or the like in thesubstrate of the equipment, the motor can be firmly mounted with highefficiency and high density, thereby realizing miniaturization of theequipment and improvement of the productivity.

Further, the portable information equipment according to the inventionincludes a larger number of lands adapted for fixation of the motor ofthe equipment than the number of poles necessary for electricalconnection of the brushless motor. As a result, the motor can beretained in a wide area and at a large number of positions, whichimproves the impact resistance of the equipment.

Still further, the portable information equipment according to theinvention is configured such that the cover of the brushless motor iselectrically grounded to the substrate of the equipment, wherebyelectromagnetic noise caused by the motor drive current can be shieldedby the cover and the radiation noise be reduced.

Still further, the motor to be incorporated in the portable informationequipment according to the invention is accommodated in a tape-likepackage to be supplied, and is then surface-mounted on the substrate ofthe equipment. Therefore, the motor can be incorporated in the equipmentin a typical electronic parts assembly production line, leading toimprovement of the productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a top view of a motor according to Embodiment 1 of thepresent invention, FIG. 1b is a side view of the motor, FIG. 1c is abottom view of the motor;

FIG. 2 is a structural sectional view of the motor;

FIG. 3a is a top view showing a state in which the motor is mounted on asubstrate of equipment, FIG. 3b is a side view of this state;

FIG. 4a is a top view of a motor according to Embodiment 2 of thepresent invention, FIG. 4b is a side view of the motor, FIG. 4c is abottom view of this motor;

FIG. 5a is a geometrical top view of another motor shaped like an oval,FIG. 5b is a similar geometrical view, FIG. 5c shows two parallel lineslocated adjacent to the outer circumference of a circle, FIG. 5d shows asquare one corner of which has been cut;

FIG. 6a is a top view of yet another motor according to the presentinvention, FIG 6 b is a side view of this motor;

FIG. 7a is a top view of still another motor according to the presentinvention, FIG 7 b is a side view of this motor;

FIG. 8a is a top view of a tape-like package according to the presentinvention, FIG. 8b is a side view of this package;

FIG. 9a is a top view of a motor according to Embodiment 4 of thepresent invention, FIG. 9b is a side view of this motor, FIG. 9c is abottom view of this motor;

FIG. 10 is a structural sectional view of the motor;

FIG. 11a is a top view showing a state in which the motor is mounted ona substrate of equipment, FIG. 11b is a side view of this state;

FIG. 12a is a top view of a motor according to Embodiment 5 of thepresent invention, FIG. 12b is a side view of this motor, FIG. 12c is abottom view of this motor;

FIG. 13a is a top view of a yet another motor according to the presentinvention, FIG. 13b is a side view of the motor;

FIG. 14a is a top view showing a sequence in which motor parts areassembled on a motor base connector, FIG. 14b is a side view of thissequence;

FIG. 15a is a top view showing a state in which motors have beenassembled on the motor base connector, FIG. 15b is a side view of thisstate;

FIG 16 is a top view showing lands for fixing a motor on the substrateof equipment together with the motor and its drive circuit (brokenlines); and

FIG. 17 is a side sectional view showing the equipment (cellular phone)incorporating a motor.

DESCRIPTION OF THE EMBODIMENTS

Embodiment 1

FIG. 1a is a top view of a motor according to Embodiment 1 of thepresent invention. FIG. 1b is a side view of this motor. FIG. 1c is abottom view of this motor. FIG. 2 is a structural sectional view of themotor. FIG. 3a is a top view showing a state in which the motor ismounted on a substrate of equipment. FIG. 3b is a side view of thisstate.

In FIG. 1, a housing of a motor has a flat shape having a top surface, aside, and a bottom surface. The housing appears like an octagon as seenfrom the top surface. A sucked surface 5 a to which a suction chuck canbe opposed is located approximately at the center of the top surface.The side is surrounded by eight wall surfaces all over thecircumference.

In FIG. 2, the motor comprises a stator 1, a printed circuit board 2, abearing device 3, a rotor 4, and a cover 5. The cover 5 principallyforms the top surface and the side, and the printed circuit board 2forms part of the side and the bottom surface.

The stator 1 is formed by covering the surface of a stator core 6 withan insulating film and then winding a coil 7 around the film. Theprinted circuit board 2 comprises a double-side through-hole substrate.The printed circuit board 2 has a bottom surface, a stator mountingsurface opposed to the bottom surface, and an outer circumferentialside.

A plurality of lands 2 a, 2 e are located on the bottom surface of theprinted circuit board 2. FIG. 1c shows their shapes as seen from the topsurface. A plurality of lands 2 b are also located on the statormounting surface. A solderable metal surface 2 c is formed on the outercircumferential side. The metal surface 2 c is formed simultaneouslywith a through-hole 2 d.

The bearing device 3 and the stator 1 are coaxially fixed to the statormounting surface of the printed circuit board 2. The terminal of thecoil 7 on the stator core 6 is soldered to the land 2 b on the statormounting surface. The land 2 b is electrically connected to the land 2 aon the bottom surface via the through-hole 2 d.

The bearing device 3 is configured by a bottomed housing 8, aoil-containing metal 9, a thrust receiver 10, and a shaft 11 insertedinto the thrust receiver 10 and one end of which is fixed to the centerof the rotor 4.

The rotor 4 has a rotor yoke 12 and a magnet 13 fixed to the rotor yoke12, and the shaft 11 is fixed to the center of the rotor yoke 12. Therotor yoke 12 surrounds the periphery of the stator 1 and is rotatablysupported by the bearing device 3. The rotor 4 further has unbalancemeans. There are various means for obtaining unbalance, but thisembodiment does so by fixing a circular weight 14 to the outercircumference of the rotor yoke 12.

As described above, the cover 5 is shaped approximately like anoctagonal cup having the top surface, the side, and the end located atthe tip of the side, and is a light shell comprising a thin metal. Thecover 5 covers the rotor 4 and the end abuts on the neighborhood of theouter circumferential end of the stator mounting surface of the printedcircuit board 2. As shown in FIG. 1b, a protruding portion 5 b isfurther formed at the end and is soldered and fixed to the opposed metalsurface 2 c of the printed circuit board 2.

The motor configured as described above is directly mounted on asubstrate 101 of equipment, as shown in FIG. 3. The substrate 101 is adouble-side multilayer substrate on which other electronic parts areintegrated and mounted, but these electronic parts are omitted. Themotor 100 is 30 reflow-soldered to the lands (106, 107 in FIG. 16) ofthe substrate of the equipment via the lands on the bottom surface (2 a,2 e in FIG. 1). The land 106 functions to electrically and mechanicallyconnect to the interior of the motor, and the land 107 functions tomechanically connect to the interior of the motor and to electricallyground the cover to the substrate. The substrate 101 of the equipmenthas a motor drive circuit (IC 102 or another electronic part) thatexcites and controls the stator 1 via the terminal (the land 2 a). Themotor drive circuit drives the magnet 13 to rotate the rotor 4. Sincethe rotor 4 has the unbalance means (the circular weight 14), vibrationis transmitted to the equipment as the rotor 4 rotates, thereby enablinginformation such as a call or an alarm to be communicated to a user as abodily sense.

An example of the state in which a motor is incorporated in an equipmentis shown in FIG. 17. The motor 100 and its drive circuit 102 are mountedon a substrate 101 as described above, and the substrate 101 is fixed inthe interior of the equipment (cellular phone) 200. The equipment alsoincludes a battery 201 as its drive source.

In this manner, in the motor of this embodiment, the pairs of terminals(the lands 2 a, 2 e) are arranged on the bottom surface so as to bespaced by an insulating section. The terminals can be soldered andconnected to the substrate of the equipment by placing and heating themon the substrate, so this motor is suitable for the SMT mounting methodand can be soldered by using the reflow method. If the terminals on thebottom surface are arranged so as not to extend from the bottom sidearea to protrude from the side as shown in FIG. 1, the interval betweenthis motor and the adjacent electronic part can be reduced to enablehigh-density mounting. In addition, the terminals can further protrudeperpendicularly from the bottom surface so as to engage with holes inthe substrate of the equipment, where the terminals can be soldered toobtain a strong securing force. Essentially, however, it is desirablefor the equipment to obtain a sufficient holding force by simplysurface-connecting the motor to the substrate of the equipment, and thepresent invention is intended to meet this requirement.

The motor of this embodiment also has on the bottom surface the terminal(the land 2 e) that is not involved in electric connections. As shown inFIG. 1c, eight lands 2 a, 2 e are formed on the bottom surface, but onlyfour (the lands 2 a) of them are involved in electric connections. Thelarge number of lands can increase a coupling area for the substrate ofthe equipment and the motor to enable them to be coupled togetherfirmly. This configuration can improve an impact resistance effectedwhen the equipment is inadvertently dropped.

In addition, according to the motor of this embodiment, the plurality oflands 2 a, 2 e on the bottom surface are arranged on both sides around aline passing through the centroid of the bottom surface. In other words,the lands are arranged point-symmetrically. In may cases, the centroidof the bottom surface approximately aligns with the center of gravity ofthe motor, but the force obtained by synthesizing the holding forces ofthe terminals can be allowed to align with the center of gravity byarranging the terminals point-symmetrically. That is, an impact forcecan be evenly distributed to each terminal to maximize the impactresistance effected when the equipment is inadvertently dropped. Thus, afirst point for improving the impact resistance is a technique forfirmly supporting the motor using the solder-joined structure betweenthe bottom surface of the motor and the substrate of the equipment.

In addition, the motor of this embodiment is approximately entirelysurrounded by the enclosure. Thus, the inside of the motor can beprotected from hot blasts or infrared rays used to melt a solder duringa reflow process to prevent the internal motor structure from beingdestroyed by heating. Consequently, the heat resistance is improved toprovide a motor preferable for the reflow soldering method. Since thebottom surface comprises a printed circuit board, the motor has a highheat resistance, an excellent heat insulating capability, and a smallweight. In addition, the housing provides an easy-to-handle shape, sothe motor can be efficiently mounted on the substrate of the equipment.Furthermore, it can prevent the entry of dust and thus a motor lockcaused by dust to maintain the reliability of the motor.

In the brushless outer-rotor motor, the rotor has the function of acover. There is no brush commutator mechanism to be protected, and thestator and the bearing device are covered by the rotor. Accordingly,there is conventionally no need to provide a cover. The presentinvention provides the external shape and the cover with many functionsto create the brushless motor suitable for the SMT mounting method andthe reflow method.

The motor of this embodiment also has the stator core 6 and the coil 7wound around the stator core 6, and the rotor 4 rotatably surrounds theperiphery of the stator 1. That is, the motor employs the cored outerrotor structure. This structure provides a magnetic circuit with ahigher permeance than the coreless structure, and provides the sameoutput using a smaller magnet. As a result, this structure can reducethe weight of the rotor and thus loads on the bearing device to improvethe impact resistance. The reduced weight of the rotor is a second pointfor improving the impact resistance. As regards this, a planar opposedcoreless motor and a cored outer-rotor motor having the same outerdiameter and approximately the same characteristics were experimentallyproduced and compared to find that the magnet weight was 1.05 gw and0.37 gw, respectively. In this manner, the cored outer-rotor type servesto reduce the weight of the rotor. If the weight is reduced by, forexample, 0.5 gw, the loads on the bearing device can be reduced by 10kgf in an environment of 20,000 G. Since the bearing device of thismotor is very small, the reduction of the loads by 10 kgf issignificant.

In addition, the cored outer rotor structure is flat and low. That is,this structure has its center of gravity at a low position.Consequently, when an impact force is effected in a direction parallelwith the substrate of the equipment, a smaller moment is imparted to theterminal connections in a direction in which they are peeled off. Thus,this structure improves the impact resistance compared to a high profileof the same mass.

In addition, the motor of this embodiment has no brush commutatormechanism. Accordingly, it requires no axial space for this mechanismand can be made flat and low easily. As a result, for the same reason asdescribed above, this structure improves the impact resistance comparedto a high profile of the same mass. Naturally, this motor is notsubjected to deformation or destruction of the brush commutatormechanism. Consequently, the internal structure can be made strong andsimple to improve the impact resistance of the motor. Furthermore, thefunctions of the rectifying mechanism are prevented from decreasing dueto a soldering or flux atmosphere, so this motor is preferable for thereflow soldering method.

As described above, a high impact resistance is obtained by using manytechniques such as the technique for firmly supporting the motor usingthe soldered structure between the bottom surface of the motor and thesubstrate of the equipment, the light rotor, the low profile, the lighthousing (cover and printed circuit board), and the simple structure.

In addition, in the motor of this embodiment, the sucked surface 5 a towhich a suction chuck (an air chuck) can be opposed is providedapproximately at the center of the top surface. According to thisembodiment, the sucked surface is a circular flat surface of diameterabout 6 mm. This surface can be used to suck and chuck the top surface.Since the air chuck is a chuck method that avoids interfering with theadjacent electronic part, the interval between the motor and theadjacent electronic part can be reduced. As a result, the motor can beefficiently mounted so as to achieve a high density.

In order to check the rotor for rotations, a hole may be formed at thecenter of the top surface to expose the shaft, but even in this case, aring-like sucked surface enables easy air chucking. In addition, the airchuck is flexible, so it can also chuck a sucked surface that is notnecessarily flat.

In addition, in the motor of this embodiment, the side includes twoparallel planes 5 c extending approximately perpendicularly to thebottom surface. If the planes 5 c reach the top surface, part of theside located near the top surface of the motor can be gripped forloading to eliminate the need to chuck the neighborhood of the bottomsurface, thereby precluding the grip chuck from interfering with theadjacent electronic part. Consequently, the interval between the motorand the adjacent electronic part can be reduced to enable the motor tobe mounted efficiently so as to achieve a high density. Furthermore,this linear portion of the contour of the motor enables alignmentwithout interference from the grip chuck. In this manner, alignment isfacilitated and can be checked easily to improve the accuracy inmounting position and direction. Thus, the motor can be mounted on thesubstrate of the equipment so as to achieve a high density.

In addition, the motor of this embodiment appears like an octagon asseen from the top surface. This shape is similar to the circular shapeof the rotor and occupies a smaller area of the substrate of theequipment. It also enables easy gripping and alignment. Thus, the motorcan be mounted on the substrate of the equipment so as to achieve a highdensity.

In addition, in the motor of this embodiment, the material of the topsurface (that is, the cover 5) is preferably a ferromagnetic substance(such as a steel plate). Such a top surface accommodates a magneticchuck and enables the use of chuck means that replaces the air and gripchucks. This top surface is also convenient in forming a marking thatuses magnetic reactions. The marking has only to be have a shapedifferent from the periphery.

Furthermore, in the motor of this embodiment, a marking that enables themounting direction to be determined is provided on the top surface orthe side. This configuration enables the mounting direction to becontrolled for automatic loading. Even if the motor is packaged orsupplied in the incorrect direction, the marking enables determinationof the direction in which the motor is mounted. Thus, the motor can bemounted on the substrate of the equipment so as to achieve a highdensity. The marking according to this embodiment is a black stamp thatexhibits a reflectance different from that of the periphery.

The marking may protrude or be recessed relative to the periphery.Advantages of such a marking are that it can be formed simultaneouslywith the member forming the top surface or the side (in this embodiment,the cover), using a mold for producing this member and that it canaccommodate any of visual checking, a magnetic reaction, and a heightsensor. This marking may be a method exhibiting a magnetic reactiondifferent from that of the periphery, for example, a magnetic ink.

This motor has such an effective loading chuck to enable accuratealignment and mounting without directional errors. These functionsprovided for the housing enable the motor to be efficiently mounted onthe substrate of the equipment like other solid electronic parts and tobe placed close to them so as to achieve a high density.

The portable information equipment according to the invention isconfigured so that the motor cover is electrically grounded directly tothe substrate of the equipment. As a result, electromagnetic noise, ofwhich source is the stator core of the motor and the coil woundtherearound, is shielded by the cover, as well as the cover and thesubstrate are mechanically combined to improve the impact resistance ofthe motor.

Embodiment 2

FIG. 4a is a top view of another motor according to the presentinvention. FIG. 4b is a side view of this motor. FIG. 4c is a bottomview of this motor.

As shown in the figures, the motor of this embodiment has protrudingterminals 25 d protruding outward from the side. The protrudingterminals 25 d are formed by further extending the protruding portion ofthe cover 25. As shown in FIG. 4c, the eight lands 22 a, 22 e arelocated on the bottom surface and the protruding terminals 25 d areadded to these lands. As is apparent from FIG. 4b, the protrudingterminals 25 b are approximately flush with the lands 22 a, 22 e. Whenplaced on the substrate of the equipment and reflow-soldered to it, themotor is fixed by means of the large number of terminals to obtain ahigher holding strength.

In addition, although not shown, a structure can be employed in whichthe protruding terminals alone can provide both a mechanical junctionfunction and an electric connection function. The protruding terminalscan be joined with the substrate of the equipment using the reflowmethod of selectively heating only the terminals without heating themotor body. This method can reduce an increase in the temperature of theinside of the motor to enable reflow soldering without destroying themotor despite the presence of a motor component of a low heatresistance.

Variation of Embodiments 1 and 2

This section shows a variation of the planar shape. FIG. 5a is a topview of yet another motor that appears like an oval as seen from the topview. FIG. 5b shows a shape similar to that in FIG. 5a. FIG. 5c shows ashape in which two parallel lines are located adjacent to the outercircumference of a circle. FIG. 5d shows a square one corner of whichhas been cut. The similar shape in FIG. 5b is obtained by cutting acircle using two parallel lines.

An oval or a similar shape is similar to a circle, so such a motor ischaracterized in that it can save space and be gripped and in that ithas an internal space and is preferred in case of further incorporatingelectronic parts within the motor. The shape in FIG. 5c is very similarto a circle and saves space, thereby reducing an area of the substrateof the embodiment that is occupied by the motor. The shape in FIG. 5dcan also be used as a marking for determining the direction.

FIG. 6a is a top view of a yet another motor according to the presentinvention. FIG. 6b is a side view of this motor. FIG. 7a is a top viewof a still another motor according to the present invention. FIG. 7b isa side view of this motor.

The motor in FIG. 6 is formed by placing a cylindrical cover 45 on anoctagonal printed circuit board 42. Since only the neighborhood of thebottom surface comprises the planar portion of the side of the motor,the top surface side is difficult to grip. Even in this case, however,an air chuck can be used to chuck the top surface to transfer the motor,and the position or direction can be corrected during the transfer. Thisstructure is advantageous in that the cover 45 requires only low costs.

The “two parallel ridges located on the side and extending parallel withthe bottom surface” set forth in the claims are, for example, ridges 42f in FIG. 6. These may be ridges 42 g. Alignment can be carried out bygripping and pressing these ridges using a grip chuck. In this case,however, the bottom or top surface must be supported.

The motor in FIG. 7 is formed by placing an arch-shaped cover 65 on anoctagonal printed circuit board 62. This structure cannot protect theinside of the motor from heat but reduces the weight and costs whilesaving resources. It can also reduce the occupied area of the printedcircuit board 62.

Embodiment 3

FIG. 8a is a top view of a tape-like package according to the presentinvention. FIG. 8b is a side view of this package.

As shown in the figures, a large number of embosses 111 are arranged inseries in a tape-like package 110, with a flat vibrating motor 120accommodated in each of the embosses. After accommodation, the embossesare covered with a film (not shown in the drawings). The package 110also has sprockets 112 (feed holes) the sizes of which conform to theindustrial standard. The package 110 is wound around a reel for supply.To mount the motors 120 on the substrate of the equipment, the motorsare sequentially loaded using the reel.

Due to this packaging form suitable for automatic supply, these motorscan be efficiently mounted on the substrate of the equipment using anautomatic machine. This enables highly efficient collective assemblyproduction of the equipment incorporating electronic parts including themotor. As described above, the present invention has cleared of theconventional brushless motor and altered the external shape, theinternal structure, and even the supply form so that the motor can behandled like other solid electronic parts.

Embodiment 4

FIG. 9a is a top view of a motor according to Embodiment 4 of thepresent invention. FIG. 9b is a side view of this motor. FIG. 9c is abottom view of this motor. FIG. 10 is a structural sectional view ofthis motor. FIG. 11a is a top view showing a state in which the motor ismounted on a substrate of equipment. FIG. 11b is a side view of thisstate.

In FIG. 9, a housing of a motor has a flat shape having a top surface, aside, and a bottom surface. The housing appears like an octagon as seenfrom the top surface. A sucked surface 5 a to which a suction chuck canbe opposed is located approximately at the center of the top surface.The side is surrounded by eight wall surfaces all over thecircumference.

In FIG. 10, the motor comprises a stator 1, a printed circuit board 2, abearing device 3, a rotor 4, and a cover 5. The cover 5 principallyforms the top surface and the side, and the printed circuit board 2forms part of the side and the bottom surface.

Although the vibrating motor of Embodiment 1 fixes a circular weight 14to the outer circumference of a rotor yoke 12 as means for obtainingunbalance, the flat brushless motor of Embodiment 4 does not include theweight 14 because it is unwanted. Another major difference is that ashaft 11 is structured so that part 111 a of it protrudes from the topsurface of the cover in order to output a rotational drive force to theexterior of the motor and that part of a housing 8 protrudes from thebottom surface as a positioning member 8 a.

This equipment has an infrared sensor function, and the motor is used asa chopper for infrared rays impinging on the sensor. An external drivemeans (a protruding portion 11 a of the shaft) protrudes from the topsurface to rotate a shading disc 103 attached to the external drivemeans, at a specified rotation speed. An infrared ray receiving element104 is located behind the shading disc 103, and light incident on theinfrared ray receiving element 104 is controlled by the motor 105.

In addition, since an air chuck is flexible, it can also chuck a surfacethat is not necessarily flat. This embodiment has a surface that can besucked, in the outer circumference of a sucked surface 5 a, and thissurface can be chucked. Even in this case, a ring-like sucked surfaceenables easier air chucking.

Embodiment 5

FIG. 12a is a top view of a motor according to the present invention.FIG. 12b is a side view of this motor. FIG. 12c is a bottom view of thismotor.

As shown in the figures, the motor of this embodiment has protrudingterminals 25 d protruding outward from the side, compared to the motorin Embodiment 4. The protruding terminals 25 d are formed by furtherextending the protruding portion of the cover 25. As shown in FIG. 12c,the eight lands 22 a, 22 e are located on the bottom surface and theprotruding terminals 25 d are added to these lands. As is apparent fromFIG. 12b, the protruding terminals 25 b are approximately flush with thelands 22 a, 22 e. When placed on the substrate of the equipment andreflow-soldered to it, the motor is fixed by means of the large numberof terminals to obtain a higher holding strength.

Embodiment 6

FIG. 13a is a top view of a yet another motor according to the presentinvention. FIG. 13b is a side view of this motor.

The motor in FIG. 13 is formed by placing an arch-shaped cover 65 on anoctagonal printed circuit board 62. Although this structure cannotprotect the inside of the motor from heat but reduces the weight andcosts while saving resources. It can also reduce an area of the printedcircuit board 62 that is occupied by the motor. Since the rotor ispartly exposed, the exposed portion can be used to frictionally drivethe equipment.

The “two parallel ridges located on the side and extending parallel withthe bottom surface” set forth in the claims are, for example, ridges 42f in FIG. 13. These may be ridges 42 g. Alignment can be carried out bygripping and pressing these ridges using a grip chuck. In this case,however, the bottom or top surface must be supported.

In this manner, since the motor of the present invention can besurface-mounted on the substrate and has other excellent characteristicssuch as a very small size and weight and a high impact resistance, thismotor can be used for various applications that take advantage fromthese characteristics. The applications may include portable informationequipment, portable game equipment, head mount displays, and fans forlocally cooling the substrate of the equipment.

Embodiment 7

FIG. 14a is a top view showing a sequence in which motor parts areassembled on a motor base connector. FIG. 14b is a side view of thissequence. FIG. 15a is a top view showing a state in which motors havebeen assembled on the motor base connector. FIG. 15b is a side view ofthis state.

In this embodiment, taking the same motors as described in Embodiment 1(FIGS. 1 and 2) by way of example, a method for assembling these motorswill be described with reference to FIGS. 14 and 15.

These motors are characterized by being assembled by using a motor baseconnector. In FIG. 14, a motor base connector 20 comprises 15 bases 2(printed circuit boards 2) and their skeleton 21. This structure isobtained by punching the bases 2 in a punching process and pushing themback, as shown at the right end of FIG. 14b. This method is chiefly usedto transfer a metal part to and from a press mold. The skeleton is apunching residue that remains after punching out the metal part.

Each of the bases 2 of the motor base connector 20 produced in thismanner includes a top surface acting as a stator mounting surface; and abottom surface opposed to the top surface. An adhesive and a creamsolder are applied to the stator mounting surface beforehand to installan assembly 16 of the stator and bearing device on this surface. Therotor 4 is then inserted into the assembly, and the cover 5 isinstalled. Subsequently, a batch heating reflow soldering process iscarried out to simultaneously complete the adhesion between the base 2and the assembly 16 of the stator and bearing device, thesolder-connection between the terminal of the coil 7 and the land 2 b,and the solder-fixation between the cover 5 and the metal surface 2 c onthe outer circumferential surface of the base 2.

During this process, the end of the side of the cover 5 abuts on theouter circumferential end of the base, and the protruding portion 5 b isinserted into an oval through-hole 23 in the boundary between the base 2and the skeleton 21. The protruding portion 5 b is solder-fixed to themetal surface 2 c that has been formed in the oval through-hole 23.

Once motors have been assembled as shown in FIG. 15, a probe is appliedto the lands 2 a on the bottom surface of each motors for inspections.Acceptable products are provided with the marking 15 and areindividually removed as shown at the right end of FIG. 15b, followed bypackaging for shipment.

Alternatively, the motors may be shipped without being removed. In thiscase, since the aligned motors are supplied, they can be convenientlymounted on the equipment using an automatic assembly machine.

As described above, the motor of this embodiment is assembled by usingthe motor base connector 20 to place each part thereon. This methodaccurately positions and holds the motor base 2 to eliminate the needsfor alignment, inversion, rearrangement, and base pallets, therebyimproving productivity, In addition, no shearing is used to remove thecompleted motor from the skeleton 21. Thus, no impact associated withshearing occurs, thereby preventing the quality of the motor from beingdegraded. In addition, this motor has excellent characteristics that itis not limited in outer-diametral shape and that it is suitable for sizereduction because its external shape can be formed with a mold accuracy.

In addition, since the motor of this embodiment uses the motor baseconnector 20, the skeleton 21 holds the bases 2 to eliminate the needsfor extra materials such as bridges. Consequently, the base costs can bereduced. In addition, due to the lack of the need to cut bridges, nospace is required for a cutting edge, thereby preventing distortioncaused by stress resulting from cutting. As a result, the base can befully used to arrange parts. Alternatively, the required area can beminimized to reduce the size and weight of the motor. Due to the lack ofconstraints on connections such as the use of bridges, the base can beshaped arbitrarily. In addition, since the external shape can be formedwith the mold accuracy, this motor can be produced accurately and issuitable for size reduction.

In addition, the base 2 of the motor of this embodiment comprises adouble-side printed circuit board. The plurality of lands are located oneach of the bottom surface and the stator side so that the mutuallycorresponding lands are connected via the through-holes. Accordingly, noother electric connection members are required, thereby enabling thestator to be compactly connected to an external connection terminal andreducing the size and weight of the motor. Furthermore, the double-sideprinted circuit board is suitable for the present method because itssolder heat resistance and a mechanical strength are high, because itsouter circumferential side can be held, and because it is subjected tolittle warpage due to its symmetry in the thickness direction. Thus,this invention can provide motors of a high quality and productivity.

In this manner, the motor of the present invention does not use thesubstrate as a simple electric wiring member but as a principalstructure (base) for the motor to reduce the number of parts requiredand the weight. Furthermore, the base comprises a plate-like substrateusing an electric insulating material as a base material. The use of theelectric insulating material enables the use of a structure comprisingmotor components on one surface of the substrate and external connectionterminals on the other surface, thereby enabling required functions tobe arranged compactly. The strength of this substrate lower than that ofa metal substrate is compensated for by reducing the weights and sizesof all parts.

In addition, since the motor is structured to expose the outercircumferential aide of the base, it can be continuously held in theconnector until it is completed. Furthermore, the substrate is heldusing the pushback method, which is most suitable for reducing the sizeof the substrate while increasing the accuracy. According to the presentstructure, the motor is assembled by using the connected substrateintended for the above usage and simply and sequentially placing partson one surface of the substrate. Furthermore, the fixation and junctionof all parts is completed by simply reflow-heating the assembly. In thismanner, the flat brushless motor having a reduced size and weight and animproved productivity has been completed.

As is apparent from the above description, the flat brushless motor issuitable for the SMT method and is preferred for the reflow solderingmethod for the following reasons:

(a) The terminals are structured so as to be solder-connected to thesubstrate of the equipment by placing and heating the motor on thesubstrate.

(b) The internal motor structure is not destroyed by infrared heatingand hot blast heating.

(c) The motor quality is not degraded by a solder or the fluxatmosphere. In addition, the motor can be efficiently mounted on thesubstrate of the equipment for the following reasons:

(d) It has an easy-to-handle shape.

(e) It can be transferred using a chuck.

(f) Its direction can be determined when the motor is mounted.

(g) The packaging form is suitable for automatic supply. In addition,the motor can be mounted on the substrate of the equipment so as toachieve a high density for the following reasons:

(h) It serves to reduce an area of the substrate of the equipment thatis occupied by itself.

(i) It serves to reduce the interval between itself and the adjacentelectronic part. Furthermore, the motor can be provided with a highimpact resistance for the following reasons:

(j) It can be coupled firmly to the substrate of the equipment.

(k) An impact force can be evenly supported by each terminal.

(l) The internal structure can be simplified.

(m) The weight of the rotor can be reduced.

(n) The height of the motor can be reduced.

In addition, the present invention uses the skeleton to hold the motorbase for assembly, thereby eliminating the needs for an extra space forshearing as in the bridge method to enable the size and weight to bereduced. In addition, no impact that is associated with shearing andseparation of completed products occurs, so a high quality can bemaintained.

In addition, since the base of this motor comprises an insulating plate,the motor is light, small, and compact. It also has an improvedproductivity because it can be held and assembled as described above.

As a result, portable information equipment comprising the flatbrushless motor according to the present invention has a reduced sizeand weight, an improved productivity, and increased added values,compared to the prior art.

What is claimed is:
 1. A brushless motor comprising: a housingcomprising a bottom surface, a side surface, and a top surface, saidbottom surface being located adjacent and opposite to a substrate of anequipment; and pairs of terminals on the outer side of said bottomsurface that can be mechanically or electrically joined with saidsubstrate of the equipment, each of said pairs of terminals beingarranged on both sides with respect to a line passing through thecentroid or center of gravity of the bottom surface, wherein there areprovided a stator, a bearing device, and a rotor inside said housing,said stator having a stator core and a coil wound around the statorcore, said rotor having a magnet and being supported by said bearingdevice so as to rotatably surround the periphery of said stator, andwherein there is provided an external drive means protruding upward frompart of the housing and rotating with the rotor.
 2. The brushless motoraccording to claim 1, having a positioning member protruding downwardfrom the bottom surface.
 3. A brushless motor comprising: a housingcomprising a bottom surface, a side surface, and a top surface, saidbottom surface being located adjacent and opposite to a substrate of anequipment; and pairs of terminals that protrude outward from said sidesurface approximately at the same height as the bottom surface and thatcan be mechanically or electrically joined with said substrate of theequipment, each of said pairs of terminals being arranged on both sideswith respect to a line passing through the centroid or center of gravityof the bottom surface, wherein there are provided a stator, a bearingdevice, and a rotor inside said housing, said stator having a statorcore and a coil wound around the stator core, said rotor having a magnetand being supported by said bearing device so as to rotatably surroundthe periphery of said stator, and wherein there is provided an externaldrive means protruding upward from part of the housing and rotating withthe rotor.
 4. A brushless motor comprising: a housing comprising abottom surface, a side surface, and a top surface, said housingincluding a chuck section, said bottom surface being located adjacentand opposite to a substrate of an equipment; and pairs of terminals onthe outer side of said bottom surface or said side surface that can bemechanically or electrically joined with said substrate of theequipment, each of said pairs of terminals being arranged on both sideswith respect to a line passing through the centroid or center of gravityof the bottom surface, wherein there are provided a stator, a bearingdevice, and a rotor inside said housing, said stator having a statorcore and a coil wound around the stator core, said rotor having a magnetand being supported by said bearing device so as to rotatably surroundthe periphery of said stator, and wherein there is provided an externaldrive means protruding upward from part of the housing and rotating withthe rotor.